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New Scientist Live

Make tough tasks seem easier by zapping the brain

MY, WHAT big eyes you have – you must be really strong. A study of how pupils dilate with physical effort has allowed scientists to make physical tasks seem easier by zapping specific brain areas.

We know pupils dilate with mental effort. To see if this was also true of physical exertion, Alexandre Zenon at the Catholic University of Louvain in Brussels, Belgium, measured the pupils of 18 volunteers as they squeezed a device which measures grip strength. The more force they exerted, the larger their pupils.

To test whether pupil size was related to actual or perceived effort, the volunteers were asked to squeeze the device with four different grip strengths. Various psychological measures enabled the researchers to tell how much effort participants felt they used.

The results suggested that pupil dilation correlated more closely with perceived effort than actual effort (Frontiers in Behavioral Neuroscience, doi.org/vrt).

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The fact that both mental effort and perceived physical effort are reflected in pupil size suggests there is a common representation of effort in the brain, says Zenon.

The team identified the brain area involved by looking at which parts were active while grip tasks were being performed. They used a non-invasive method called transcranial magnetic stimulation to block activity in that area as people repeated the task. “When we disrupted this area, there was a clear drop in the perception of effort,” says Zenon. The study shows that, in theory, it is possible to make some tasks seem less effortful, he says.

This article appeared in print under the headline “Can you think yourself into being stronger?”